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首页> 外文期刊>Combustion Science and Technology >Effect of ethylene fuel/air equivalence ratio on the dynamics of deflagration-to-detonation transition and detonation propagation process
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Effect of ethylene fuel/air equivalence ratio on the dynamics of deflagration-to-detonation transition and detonation propagation process

机译：乙烯燃料/空气当量比对爆燃-爆轰过渡和爆轰传播过程动力学的影响

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摘要

During the operation, the pulse detonation engine (PDE) may have to work with different fuel/air equivalence ratios (from a lean to rich fuel mixture) as in the cold start-up operation, which would strongly affect the engine performance characteristics and the outputs of interest. For a better operational control, it is necessary to gain understanding of the effect of the equivalence ratio on the dynamics of the processes of PDE. Thus, in this study, numerical simulations are performed for different ethylene fuel/air equivalence ratios to study its effect on the dynamics of the deflagration-to-detonation transition (DDT) and detonation processes. In particular, the density-based solver with a shock-capturing scheme is employed to solve for the viscous, compressible, and reacting flows governed by reacting Navier-Stokes equations. The computed flame propagation speed, run-up distance, and Chapman-Jouguet detonation velocity are comparable to the current experimental results. In addition, the numerical results show that the minimum values of the run-up distance and run-up time, as well as the maximum value of the detonation velocity occur at the equivalence ratio of about 1.1. Analysis of the computed results associate these findings to the firm correlation of the flame speed with equivalence ratio, which is in turn function of the temperature, pressure, and mixture composition. The shifting of the outputs of interest to the richer fuel side from the stoichiometric point can be attributed to the combustion product dissociation, mixture heat capacity, and oxidizer enrichment.
机译：在运行期间，脉冲爆震发动机（PDE）可能必须像在冷启动操作中一样，以不同的燃油/空气当量比（从稀薄到浓混合气）工作，这会严重影响发动机的性能和感兴趣的输出。为了获得更好的运行控制，有必要了解当量比对PDE过程动力学的影响。因此，在这项研究中，对不同的乙烯燃料/空气当量比进行了数值模拟，以研究其对爆燃-爆轰过渡（DDT）和爆轰过程动力学的影响。尤其是，采用具有震荡捕获方案的基于密度的求解器来求解由Navier-Stokes方程控制的粘性，可压缩和反作用流。计算得出的火焰传播速度，加速距离和Chapman-Jouguet爆轰速度与当前的实验结果相当。此外，数值结果表明，加速距离和加速时间的最小值以及爆震速度的最大值以大约1.1的当量比出现。对计算结果的分析将这些发现与火焰速度与当量比的牢固关联相关，当量比又是温度，压力和混合物成分的函数。感兴趣的输出从化学计量点向富燃料侧的转移可归因于燃烧产物的离解，混合物的热容量和氧化剂的富集。

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